Power management integrated circuits (ICs) have been developed that are to be embedded into portable consumer electronics devices such as smart phones and tablet computers. Different functions have been integrated onto a power management IC chip. For example, high efficiency switch mode battery charger circuitry has been embedded into a power management IC, which interfaces directly with the rechargeable battery of the portable device. The charger circuitry executes constant current/constant voltage charging profiles upon the battery, without requiring interaction with the main processor, so as to efficiently bring the battery up to a state of full charge. On-chip power control or power switching circuitry controls a battery charging current according to a specified constant current (CC) and constant voltage (CV) profile. The IC chip may also have voltage regulator circuitry that provides regulated dc output voltages for use by other active components of the portable device. Digital communication interfaces are also provided that allow battery charging and power management commands to be received from the main processor. The typical power management IC also has an interface to a separate peripheral power source, such as a USB host, from which it draws current to charge the battery and supply its on-board voltage regulators.
Typically, the battery is offered as a battery pack or assembly that contains a battery temperature sensor and a battery gas gauge circuit integrated together with at least one rechargeable electro-chemical battery cell. A separate or dedicated signal wire connects the battery temperature sensor to analog temperature monitoring circuitry within the power management IC, which allows the battery charging control circuitry to automatically avoid overheating the battery during charging at normal temperatures, or charging at low temperatures which may reduce cell life. The charging circuitry in the power management IC directly monitors the battery terminal voltage and the charge current, to implement the set CV and CC charging profile. A single wire digital communications interface (SWI) connects the gas gauge to the main processor, through which the main processor monitors battery voltage, state of charge data, and charge-discharge or usage cycle count received from the gas gauge, in order to compute for example time-to-empty and a measure of the health of the battery.